Typical cable connections are usually achieved by soldering a cable's central, conductive metal core member or its metallic, braided shield to a connector. The central, conductive metal core member and the metallic shield layer are easily soldered to a connector, the latter of which usually comprises copper metal wires.
It has recently been suggested that the central, conductive core of cables or the braiding of their shield layers be replaced by conductive polymers, or, fiber strands that are thinly coated with metal. The object of this new construction is to produce cables of thinner cross-section and lighter weight. Such conductive fibers provide cable that is more flexible and of higher tensile strength than is standard cable. This type of cable can be quite advantageous in aerospace applications.
Cable having a central, conductive, polymeric fiber core is disclosed in U.S. patent application Ser. No. 07/797,585, filed on Nov. 11, 1991 now U.S. Pat. No. 5,218,171, issued Jun. 8, 1993, for "Wire and Cable Having Conductive Fiber Core" and is assigned to a common assignee. The aforementioned patent application discloses the use of metal-coated fibers comprising Aramid. These high-tensile strength fibers are stranded in order to provide a central conductive core for the cable.
Cable having a braided or served conductive fiber shield layer is disclosed in U.S. patent application Ser. No. 07/624,952, filed on Dec. 10, 1990, now abandoned for "Non-Halogenated Insulation Composite" and is also assigned to a common assignee.
One of the problems in trying to adapt this type of cable for commercial usage is that it cannot be directly soldered to conventional electrical connectors, due to the incompatibility of the fiber's thin metal coat, which is only a few micrometers in thickness. The thinness of the metal coat does not provide enough structural metal to produce a strong solder bond. In addition, the temperature of the molten solder easily oxidizes this thin metal coat, resulting in a resistance contact that is too high for such connections.
The present invention features a cable assembly wherein the metal-coated fibers of the central, conductive core member or shield layer are connected to a newly styled connector via a crimpable intermediate sleeve. This new connector features a first portion comprising an internal, concave, bullet-shaped recess, and a second portion comprising an external, deformable shell. The intermediate sleeve comprises a bifurcated component having a first section made of a solid, convex, bullet-nose portion that fits into the concave, bullet-shaped recess of the newly styled connector, mating therewith; the second section of the sleeve consists of a hollow tube-like portion that fits over the core member or the braided shield layer and is deformably crimped thereto. The second section of the sleeve can be attached to the cable by crimping it over the core or shield layer. The bullet-nose portion of the sleeve is solderable to the connector once the connector's external, deformable shell has been fitted over the sleeve and crimped thereto. The double crimp between the connector and the sleeve, and the sleeve and the central core or shield, provides a double mechanical bond between the central core member or shield, the sleeve, and the connector. Such double crimping, in combination with the soldered bond, provides a very strong mechanical bond.
Furthermore, the connector assembly of this invention need not be discarded, should the connector need replacement or the core member require reconnection. The soldered connection to the connector can be broken by reheating, and the bullet-nose portion of the sleeve reinserted into a new connector element.
The connector assembly of this invention can be utilized with central conductive core members of any size and shield layers of any thickness.